Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 201203
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
803 AM EDT SAT SEP 20 2014

.SYNOPSIS...A LOW PRESSURE SYSTEM WILL TRACK SLOWLY NORTHEAST ALONG
THE CAROLINA COAST THROUGH SUNDAY AS A COLD FRONT APPROACHES THE
MOUNTAINS FROM THE WEST. HIGH PRESSURE WILL BUILD INTO THE REGION
FROM THE NORTH EARLY TO MID NEXT WEEK...IN THE WAKE OF A DRY COLD
FRONTAL PASSAGE MONDAY MORNING.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 230 AM SATURDAY...

AN UPPER LEVEL TROUGH EXTENDING NORTHEAST FROM THE FL PANHANDLE INTO
CENTRAL PORTIONS OF THE CAROLINAS WILL TEMPORARILY STALL OVER THE
REGION THROUGH TONIGHT. DPVA ON THE EASTERN PERIPHERY OF THE UPPER
LEVEL TROUGH WILL FOSTER CYCLOGENESIS ALONG A BAROCLINIC ZONE
PRESENT ALONG/JUST OFFSHORE THE FL/GA COAST TODAY...WITH GRADUAL
STRENGTHENING OF THE SFC CYCLONE AS IT TRACKS SLOWLY NORTHEAST
OFFSHORE THE SC/NC COAST TONIGHT. EXPECT INCREASINGLY CLEAR SKIES
WITH WESTWARD EXTENT FROM THE HWY 1 CORRIDOR WHERE SYNOPTIC
SUBSIDENCE WILL PREVAIL ON THE WESTERN PERIPHERY OF THE STALLED
UPPER LEVEL TROUGH WHERE FCST SOUNDINGS (I.E. AT INT/GSO) INDICATE A
DRY COLUMN AND PRONOUNCED MID-LEVEL SUBSIDENCE INVERSION. ALTHOUGH
MOISTURE WILL INCREASE AND MID-LEVEL TEMPS WILL DECREASE HEADING
EAST TOWARD THE COAST...CENTRAL NC WILL LARGELY REMAIN ON THE
SUBSIDENT SIDE OF THE UPPER LEVEL TROUGH...WITH THE BEST CHANCE OF
PRECIPITATION ALONG THE CAROLINA COAST....THOUGH ISOLD SHOWER
ACTIVITY CANNOT BE RULED OUT IN THE FAR SE COASTAL PLAIN WHERE LOW-
LEVEL MOISTURE ADVECTION FROM THE ATLANTIC AND DIURNAL HEATING
RESULT IN MARGINAL DESTABILIZATION. WILL INDICATE A DRY FORECAST
EVERYWHERE EXCEPT PERHAPS A SLIGHT CHANCE OF LOW-TOPPED SHOWERS IN
SAMPSON/WAYNE/CUMBERLAND OR SAMPSON ALONE WITH HIGHS IN THE LOWER
80S. DRY CONDITIONS WILL PREVAIL EVERYWHERE OVERNIGHT WITH LOWS
RANGING FROM THE UPPER 50S WEST TO LOWER 60S EAST. -VINCENT

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 245 AM SATURDAY...

DRY/SUBSIDENT CONDITIONS WILL PREVAIL SUNDAY AS THE STALLED UPPER
LEVEL TROUGH BECOMES PROGRESSIVE...MOVING OFFSHORE WITH THE
ATTENDANT SFC LOW. POTENT SHORTWAVE ENERGY DIGGING THROUGH THE GREAT
LAKES INTO THE OH VALLEY WILL PROPEL A COLD FRONT EAST TOWARD THE
APPALACHIANS ON SUNDAY. THE FRONT WILL CROSS CENTRAL NC MONDAY
MORNING AS THE AFOREMENTIONED SHORTWAVE ENERGY TRACKS ACROSS THE
NORTHERN MID-ATLANTIC. POOR DIURNAL TIMING WILL LIKELY RULE OUT ANY
POTENTIAL FOR CONVECTION IN ASSOC/W THE FRONTAL PASSAGE...AND WILL
MAINTAIN DRY CONDITIONS EVERYWHERE THROUGH SUN NIGHT. HIGHS ON SUN
IN ADVANCE OF THE FRONT IN THE MID 80S...LOWS IN THE LOWER/MID 60S
GIVEN FROPA CLOSE TO SUNRISE. -VINCENT

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 330 AM SATURDAY...

DRY AND COOL TO START THE WEEK...THEN INCREASING CLOUDS/COOL LATE
WEEK...

A LARGE SPRAWLING SURFACE HIGH PRESSURE IS FORECAST TO PUSH A COLD
FRONT THROUGH OUR REGION EARLY MONDAY. MODELS ARE IN GOOD AGREEMENT
IN DEPICTING THE LACK OF MOISTURE ASSOCIATED WITH THE FRONTAL
PASSAGE. THEREFORE... ESSENTIALLY NIL POP AND QPF FOR MONDAY. GOOD
DRY AND COOL AIR ADVECTION WILL COMMENCE LATER MONDAY THROUGH
TUESDAY. DRY AND COOL CONDITIONS ARE FORECAST INTO WEDNESDAY
COURTESY OF THE STRONG HIGH.

MODELS HAVE YET TO RESOLVE DIFFERENCES IN SOLUTIONS FOR MID TO LATE
WEEK. SEVERAL OPERATIONAL MODELS INDICATE A WEAKNESS ALOFT OVER THE
SOUTHERN APPALACHIANS OR OVER OUR REGION BY THU-FRI. SOME MODELS AND
ENSEMBLES HAVE LESS IN THE WAY OF A WEAKNESS ALOFT. REGARDLESS... IT
DOES APPEAR THAT MOISTURE WILL BEGIN TO INCREASE FROM OFF THE
ATLANTIC AS THE SURFACE HIGH SHIFTS OFF THE NEW ENGLAND COAST
ESPECIALLY LATE WED INTO THU. JUST HOW DEEP THIS MOISTURE BECOMES
SHOULD BE DETERMINED BY THE HEIGHTS ALOFT WHICH MAY NOT BE RESOLVED
FOR A FEW MODEL CYCLES.

THEREFORE... THE ONLY CHANCES MADE TO THE FORECAST WERE TO INCREASE
TEMPERATURES A BIT MONDAY WITH MORE IN THE WAY OF SUN EXPECTED
(PARTLY SUNNY SKIES... BECOMING MOSTLY SUNNY IN THE AFTERNOON)...
AND LESS POP WITH THE EARLY MORNING COLD FRONTAL PASSAGE (NOW NIL).
HIGHS GENERALLY 77-82 N TO SE.

MUCH COOLER TUE-WED WITH SOME UPPER 40S IN THE COOLER RURAL PIEDMONT
AND SANDHILLS LOCATIONS UNDER MOSTLY CLEAR SKIES AT NIGHT... THEN
HIGHS ONLY 70-75 WITH MOSTLY SUNNY SKIES.

WE WILL SHOW A TREND TOWARD INCREASING CLOUDINESS AND LOWER
AFTERNOON HIGHS THU-FRI DUE TO THE ATLANTIC FLOW AND POTENTIAL FOR A
WEAKNESS ALOFT. POP MAY HAVE TO BE INCREASED IN LATER FORECASTS IF
THE EC/CANADIAN TEND TO VERIFY BETTER.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 730 AM SATURDAY...

24-HR TAF PERIOD: ASIDE FROM CURRENT LIFR/IFR FOG AND LOW CEILINGS
WHICH WILL SCATTER OUT BY 12-14Z...VFR CONDITIONS AND A LIGHT
NORTHEAST BREEZE WILL PREVAIL THROUGH THE TAF PERIOD AT THE
INT/GSO/RDU TERMINALS...LOCATED ON THE WESTERN PERIPHERY (SUBSIDENT
SIDE) OF AN UPPER LEVEL TROUGH OVER THE SOUTHEAST. VFR CONDITIONS
WILL PREVAIL FOR MOST (IF NOT ALL) OF THE TAF PERIOD AT THE FAY/RWI
TERMINALS...EXCEPT FOR A POTENTIAL FOR MVFR CEILINGS (BASES 2500-
3500 FT AGL) AND ISOLD SHOWERS DURING THE AFTERNOON IN ASSOC/W A
MOIST LOW-LEVEL EASTERLY FLOW OFF THE ATLANTIC.

LOOKING AHEAD: ASIDE FROM A SMALL CHANCE OF AN ISOLD SHOWER AT THE
INT/GSO TERMINALS AND A 10-15 KT WESTERLY BREEZE IN ADVANCE OF A
COLD FRONT APPROACHING THE REGION FROM THE WEST LATE SUNDAY
AFT/EVE...VFR CONDITIONS (AND A NORTHEASTERLY BREEZE) WILL PREVAIL
THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE
NORTH/NW. -VINCENT

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...VINCENT
LONG TERM...PWB
AVIATION...VINCENT


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